1. National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University, Nanjing 210093, China
2. Department of Mathematics and Science, Luoyang Institute of Science and Teleology, Luoyang 471023, China
3. Center for Magnetic Materials and Devices and Key Laboratory for Advanced Functional and Low Dimensional Materials of Yunnan Higher Education Institute, Qujing Normal University, Qujing 655011, China